[Rd] 'ordered' destroyed to 'factor'

"Jens Oehlschlägel" jens.oehlschlaegel at truecluster.com
Fri Jun 16 15:03:45 CEST 2017

Dear all,
I don't know if you consider this a bug or feature, but it breaks reasonable code: 'unlist' and 'sapply' convert 'ordered' to 'factor' even if all levels are equal. Here is a simple example:

o <- ordered(letters)
lapply(o, min)[[1]]          # ordered factor
unlist(lapply(o, min))[[1]]  # no longer ordered
sapply(o, min)[[1]]          # no longer ordered

Jens Oehlschlägel
P.S: The above examples are silly for simple reproduction. The current behavior broke my use-case which had a structure like this
# have some data
x <- 1:20
# apply some function to each element
somefunc <- function(x){
  # do something and return an ordinal level
  sample(o, 1)
x <- sapply(x, somefunc)
# get minimum result
# Error in Summary.factor(c(2L, 26L), na.rm = FALSE) :
#   ‘min’ not meaningful for factors
> version
platform       x86_64-pc-linux-gnu         
arch           x86_64                      
os             linux-gnu                   
system         x86_64, linux-gnu           
major          3                           
minor          4.0                         
year           2017                        
month          04                          
day            21                          
svn rev        72570                       
language       R                           
version.string R version 3.4.0 (2017-04-21)
nickname       You Stupid Darkness        

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